Quartz dissolution is a frequent process in geochemistry and materials science. It is controlled at the atomic scale by the sequential hydrolysis reactions and breakage of siloxane bonds, the surface topography, and the Gibbs free energy difference ΔG between the solid and the solution. Atomistic simulations have provided valuable topographic information about quartz dissolution and reaction energy barriers. However, with the current interpretation of the data, serious discrepancies persist between the predicted dissolution rates R_dis and the macroscopic dissolution activation energy E_a compared to their experimental counterparts. In this work we show that both quantities can be reconciled using a kinetic Monte Carlo (KMC) atomistic model based on bond-by-bond reactions and R_dis and E_a can be jointly reproduced. In addition, the obtained etch pit shapes for different quartz planes are in agreement with the experimentally reported ones: V-shape striations in {001}, rectangular pyramidal pits in {100}, and trapezoidal semipyramidal pits in {101}. We also study the dissolution rate dependence with ΔG by introducing chemical reversibility in the KMC model, obtaining again results in good agreement with experiments. This work highlights the importance of understanding the mechanisms taking place at the nanoscale to describe macroscopic properties and provides the basic ingredients to extend this study to other minerals and/or dissolution conditions.

中文翻译：

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用于研究石英溶解的新动力学蒙特卡洛模型

石英溶解是地球化学和材料科学中的常见过程。通过顺序水解反应和硅氧烷键的断裂，表面形貌以及固体和溶液之间的吉布斯自由能差ΔG来控制原子尺度。原子模拟提供了有关石英溶解和反应能垒的有价值的地形信息。然而，根据目前的数据解释，预计的溶出速率R _dis和宏观溶出活化能E _a之间仍然存在严重差异。与实验对象相比。在这项工作中，我们表明可以使用基于键对键反应的动力学蒙特卡洛（KMC）原子模型对两个量进行协调，并且可以共同复制R _dis和E _a。另外，获得的用于不同石英平面的蚀刻凹坑形状与实验报道的一致：{001}中的V形条纹，{100}中的矩形金字塔形凹坑和{101}中的梯形半金字塔形凹坑。我们还研究了溶出度对ΔG的依赖性通过在KMC模型中引入化学可逆性，再次获得与实验良好吻合的结果。这项工作突出了理解纳米级描述宏观特性的机理的重要性，并提供了将本研究扩展到其他矿物质和/或溶解条件的基本成分。